For my class's 10-year reunion, someone created a Facebook group to track down classmates and organize the reunion.

They ignored the best availability dates given by most members and instead planned the reunion around the dates requested by the popular kids from our class. Which most people couldn't attend. Then they picked an expensive venue and asked everyone to chip in money to cover the party reservation, even if they're not planning to attend.

Suffice to say, there was apparently a very poor turnout and whomever planned the event had to pay thousands of dollars out of pocket to cover the event themselves. They were still asking for donations to help out over a year later.

My 20-year reunion went a lot better and I actually showed up for that one.